ssd maintance / types of flash memory storage

linux_ssd_maintantace_cheat_sheet.txt

#
# SSD's and flash memory is available in a variety of different flavours.
# As power drains from souch a system you stand to lose those bits!
#
# Firmware plays an important role in all of this.
# 
# If your SSD is not powered up then the firmware will not be able
# help you out. Most firmware is propriortary and as such, you can
# power the drive up for a while (...?...) and hope for the best.
#
# The best approach is to use write cycles
# delete the data and put it back. Then you will 
# have some level of certianty that the data has been 
# written again.
#
# Below are possible ways to mitigate or work around
# the problem. Best idea is if it is important
# have mulitple copies.
#
# Some quicker fixer-uper approaches, below
# may prove useful in preserving your data.
#

# if your firmware behaves
dd if=/dev/sdX of=/dev/null bs=2M 

# if your drive is offline 
dd if=/dev/sdX of=/dev/sdX bs=2M iflag=fullblock conv=sync,noerror status=progress

# zfs scrub (software checksums)
zpool scrub poolname

# btrfs (software checksums)
btrfs scrub start

# If you just want to know if bits have flipped
# then checksum your data. There are many
# ways to checksum data on a file system
# with a computer.

# fingerprint 
https://github.com/ioquatix/fingerprint

# gammar radition is problimatic and should be avoided

# video links 
  
   # error testing
  https://www.youtube.com/watch?v=rx3Y5x6uzKQ
  
  # how they are made
  https://www.youtube.com/watch?v=dX9CGRZwD-w

  # general backup and stroage tips (ask leo)
  https://www.youtube.com/watch?v=7ExvtSeyHL0&t=90s
  
  # long term storage tips (ask leo)
  https://www.youtube.com/watch?v=e7v13Zu3SXc
  

# my archival tips

   # pictures / images
   #    - best option 
   #          - print it out
   
   

types_of_flash.md

types of NAND flash memory

consumer options

• 3D NAND : about 1 year?

  • QLC (Quad-Level Cell) 3D NAND flash, which stores four bits of data per cell
  • TLC (Triple-Level Cell)

• About 3 years? - MLC (Two bits per Cell) NAND flash memory

• SLC Single-Level Cell

  • 1 bit per cell (typical)

somewhat higher end options

• eTLC (enterprise TLC) NAND Flash months?